1. Field of the Invention
The present invention relates to an input device provided with a plurality of input buttons.
2. Description of the Related Art
Examples of an input device provided with a plurality of input buttons include an electrostatic capacitance touch panel. The electrostatic capacitance touch panel is designed to perform a button operation by utilizing a change in an electrostatic capacity caused when an input object contacts or approaches an input button. In such a touch panel, one or more electrodes are provided for each input button. Each electrode is connected to a corresponding one of signal lines each for outputting an output value, so that an increase in the number of input buttons tends to increase the number of signal lines. However, since complexity of routing increases with increase in the number of signal lines, the number of signal lines is preferably small.
In light of this situation, there is known an input device in which two types of electrodes, namely, a first electrode and a second electrode constitute one input button. The input device is provided with a plurality of input buttons each as the one input button, and the first electrodes of input buttons adjacent to each other are connected to the same signal line. This design can reduce the number of signal lines. It is noted that, in the input device in which two types of electrodes constitute one input button, a button operation is performed by utilizing a combination of the first electrode and the second electrode whose electrostatic capacities have been changed.